Refrigerant accumulator with liquid separator

ABSTRACT

A refrigerant accumulator for refrigerant circuits having a container with an inlet for a two-phase mixture and an outlet for the refrigerant vapor. The accumulator includes a baffle provided as a separator in the upper part of the refrigerant accumulator. The baffle includes means for the collection of liquid refrigerant, by which the liquid refrigerant is leadable into the lower region of the refrigerant accumulator.

BACKGROUND

1. Field of the Invention

The invention relates to a refrigerant accumulator for use inrefrigerant circuits and more particularly to a refrigerant accumulatorwith a liquid separator.

2. Related Technology

Refrigerant accumulators are used in refrigeration systems or heat pumpswhich work on the principle of cold vapor process, and are placeddownstream of the evaporator. The refrigerant accumulator functions toseparate that portion of the inflowing two-phase mixture which has notyet been liquefied from the gaseous portion. To do this, it uses asuitable liquid separator. The separated liquid refrigerant and, ifpresent, the liquid refrigerator oil is accumulated or temporarilystored, respectively, in the accumulator.

Various embodiments of refrigerant accumulators are known in the art. InU.S. Pat. No. 6,564,575, the refrigerant flow entering the refrigerantaccumulator is frontally led onto a baffle plate. The liquid portion ofthe refrigerant flow is then directed to the inner wall of theaccumulator where it adheres to the inner wall due to inertia forces andwetting effects and flows downward into the storage region of theaccumulator.

According to the teachings of U.S. Pat. No. 6,430,958, a refrigerantaccumulator is disclosed in which the liquid portions of the refrigerantare led tangentially to the inner wall, eventually reaching the storageregion of the accumulator.

Various disadvantages are inherent in the state-of-the-art. Particularlyserious disadvantage is that in an environment with temperatures abovethe saturation temperature of the inflowing refrigerant, heat input intothe accumulator will occur due to the temperature gradient. If thecontainer wall of the accumulator is a component of the mechanicalseparator, the heat input may be excessive. Also if the accumulator isalmost empty, a thin film of liquid refrigerant develops at the innerwall of the container creating ideal conditions for evaporationprocesses, or heat adsorption by the refrigerant.

In U.S. 2005/0081559, a refrigerant accumulator is shown in which abaffle plate is used below the inlet of the two-phase mixture. Theliquid components hit the baffle plate, adhere to it and flow along thebaffle plate to the lower border of the baffle plate. At the lowerborder of the baffle plate drops of liquid refrigerant form and thendrop down, due to gravity, into the lower region of the container wherethey are intermediately stored.

It is disadvantageous in the above mentioned state-of-the-art that theflows of liquid and the gaseous refrigerant, after separation, are ledsuch that they cross each other. Therefore, the gaseous flow inevitablydrags a portion of the separated liquid displacing it to the outlet ofthe accumulator. This liquid bypass results in low separationefficiency. In addition, the danger of piston impact increases inrefrigerant piston compressors when the liquid phase of the refrigerant,in form of droplets, reaches the compressor.

The disadvantages of the known refrigerant accumulators increase thecirculating refrigerant mass flow, but do not increase the usefulrefrigerating or heating capacity of the machine. An increase of therefrigerant mass flow, however, has an unfavorable effect of increasingthe power input of the plant. Accordingly, the coefficient ofperformance (COP) or the efficiency of the machine gets worse.

SUMMARY

The present invention provides a refrigerant accumulator with a liquidseparator such that a high separator efficiency is achieved, whilerefrigerant mass flow is minimized by minimizing the heat input into theseparated liquid refrigerant.

According to the invention, above limitation and drawbacks are sought tobe overcome by a refrigerant accumulator having a container with aninlet for the two-phase mixture and an outlet for the refrigerant vapor.A baffle is provided as a separator in the upper part of the refrigerantaccumulator. According to the invention, the baffle is provided withmeans for collecting and leading the liquid refrigerant into the lowerregion of the refrigerant accumulator.

In an advantageous embodiment of the invention, the means for collectingthe liquid refrigerant is arranged at the lower border of the baffle. Ina particularly advantageous embodiment, the means for collecting theliquid refrigerant is configured as eaves in gutter form.Advantageously, the eaves are provided with a region for collection ofliquid refrigerant and are configured with a slope towards the region ofcollection. This ensures that the liquid refrigerant separated on thebaffle is collected at the eaves and led off towards the region ofcollection by gravity.

In an advantageous embodiment of the refrigerant accumulator, an exhaustpipe for the refrigerant vapor is configured to be without thermalcontact with the container wall, whereby advantageously the collectionregion of the baffle is connected to this exhaust pipe. The liquidrefrigerant therefore comes to the collection region over the means forcollecting the liquid refrigerant, and from the collection region flowson the exterior of the exhaust pipe downward into the accumulatorregion. It is particularly advantageous to design the exhaust pipe in aJ-shape, whereby the lower opening of the exhaust pipe is located belowand underneath the dome-like baffle, which is hit by the two-phasemixture from above.

In alternative embodiments of the invention, the baffle is configured tobe half-spherical, parabolic or cone-shaped.

The concept of the invention resides in that the exhaust of the gaseousrefrigerant is arranged such that dragging of refrigerant droplets bythe refrigerant vapors is largely prevented by design, and further, thatthe heat input into the liquid refrigerant, increasing the mass flow, isreduced by specific collecting and leading off the liquid refrigerant.

One configuration and function of a refrigerant accumulator according tothe invention can generally be described as follows: the inlet of therefrigerant accumulator for the two-phase mixture is located above thebaffle. The liquid components of the inflowing refrigerant contact thebaffle and adhere to it by adhesion forces. Hence, both phases areseparated from each other. The gaseous phase flows around through anannular gap between the baffle and the inner wall of the container andinto the container region below the baffle, where the gaseous phase isdrawn off underneath the baffle by the exhaust pipe.

The liquid phase flows across the convex surface of the baffle downwardinto a catching and flow-off gutter, generally referred to as the meansfor collecting the liquid refrigerant. In this way, no eaves, in thetraditional sense, are formed at the lower border of the baffle overwhich the liquid refrigerant would drop into the lower region of thecontainer, along the whole edge of the baffle. The liquid refrigerantand liquid oil collected in the gutter, due to sloped arrangement of thegutter/baffle, flow toward a leg of the J-shaped exhaust pipe. At theexhaust pipe, the gutter is open so that the liquid adhering to theouter surface of the exhaust pipe can flow downward along a portion ofthe exhaust pipe into the lower storage region of the accumulator,without wetting the inner surface of the container. As a result, heatinput into the accumulator is kept low because, for a low refrigerantlevel, heat can only enter the accumulator by convection but not byrefrigerant evaporation. Also, dropping liquid is prevented fromcrossing with the gas flow and being dragged by the gas flow into theexhaust.

As seen from above, the invention has various advantages. Particularlyadvantageous is that the liquid separator has a high separationefficiency since after phase separation the liquid and gas flows do notcross each other. In this way, the gas, or refrigerant vapor, leavingthe refrigerant accumulator towards the refrigerant compressor iseffectively prevented from containing liquid droplets of the two-phasemixture that flows into the refrigerant accumulator itself.

With this, the operational safety of a refrigeration plant or a heatpump, respectively, is effectively increased since the danger of pistonimpacts caused by liquid entering the compressor is minimized.

Another advantage of the present invention is in that the heat inputinto the accumulator is minimized because the inner container surface isnot used as part of the liquid separator and, hence, no heat input worthmentioning enters the accumulated liquid refrigerant over this containersurface.

The advantageous effects of the present invention are reflected in anincrease of the COP of the refrigeration machine or heat pump. Thisoccurs because the refrigerant mass flow of the plant is not increasedas a result of the operation of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Further details, features and advantages of the present invention aremade more apparent through the detailed description of the various ofembodiments, with reference to the accompanying drawings, in which:

FIG. 1 is a sectional view of a refrigerant accumulator in accordancewith the present invention;

FIG. 2 a is a schematic drawing of a baffle. similar to a hemisphere,with means for collecting the liquid refrigerant as might alternately beemployed in the refrigerant accumulator of FIG. 1;

FIG. 2 b is a schematic drawing of a hood-like baffle with means forcollecting the liquid refrigerant; and

FIG. 2 c is a schematic drawing of a circular cone-like baffle havingmeans for collecting the liquid refrigerant.

DETAILED DESCRIPTION

Referring now to the drawings, in FIG. 1 a refrigerant accumulator 10with J-shaped exhaust pipe 12 is shown in sectional view. Theaccumulator 10 includes a container 13 having a side wall 14 delimitedby an upper border in the form of a cover plate 16 with connections anda lower border in the form of a bottom plate 18.

The represented embodiment shows a circular, cylindrical side wall 14.The cover plate 16 has an inlet 20, such as a nipple, for the two-phasemixture, as well as a connection 22, such as an opening, for the outlet24 of the refrigerant vapor. The inlet 20 of the two-phase mixture isarranged approximately central at the cover plate 16 so that thetwo-phase mixture enters the container 14 from above. The enteringtwo-phase mixture is provided onto a baffle 26 from above, which in theembodiment shown is being hood-like or hemispherical, generally like anumbrella. The outer diameter of the baffle 26 is provided such that anannular gap is created between the baffle 26 and the container side wall14.

At its lower perimeter, the baffle 26 is provided with a means forcollecting the liquid refrigerant 28, which is in the form of eaves. Theeaves 28 themselves are configured gutter-like, with an up-turned edge,so that the liquid refrigerant does not drop uncontrollably from theedge of the baffle 26. The gutter-like eaves 28 are arranged around thebaffle 26 and slope downward toward one side and at the lower end isprovided with a collection region 30 for the liquid refrigerant. Thecollection region 30 for the liquid refrigerant is in connection withthe exhaust pipe 12.

The exhaust pipe 12 itself does not contact the container 13, with theexception of the connection 22 at the outlet 24 for the refrigerantvapor. This largely separates the exhaust pipe 12 from the container 13in thermal respects so that the heat input into the liquid refrigerantis minimized.

The exhaust pipe 12 is reversely bent and provided in its upper endbeing the outlet 24 in the cover plate 16 of the container 13 and, atits other end, with the exhaust inlet opening 32, which is arranged inan interior cavity 34 within the underside of the hood-like baffle 26.

Therefore, the two-phase mixture flows from the inlet 20 onto the baffle26. On the baffle 26 the liquid droplets, after wetting the baffle 26,are separated from the mixture and flow towards the periphery of thebaffle 26 where they are collected in the eaves 28. Because of the slopeof the eaves 28 the liquid refrigerant then flows in the eaves 28 to thecollection region 30 where the liquid component of the two-phase mixtureconcentrate.

The collection region 30 for liquid refrigerant is in contact to theexhaust pipe 12 so that the liquid refrigerant flows over the baffle 26,the eaves 28 and the collection region 30 towards the exhaust pipe 12.Over the connection between the collection region 30 and the exhaustpipe 12 the liquid refrigerant flows on the outside of the exhaust pipe12 downwards to the refrigerant accumulator region 36.

Advantageously, the liquid refrigerant does not flow along therelatively warm side wall 14 of the accumulator 10 downwards into therefrigerant accumulation region 36, but instead flows on the relativelycold exhaust pipe 12, through which the refrigerant vapor passes towardsthe compressor. In this way the refrigerant mass flow is notadditionally increased by evaporating refrigerant and the efficiency ofthe refrigeration process is, therefore, higher compared with otherrefrigerant accumulator concepts.

In the FIGS. 2 a to 2 c alternative embodiments of baffles areexemplarily shown. The baffles are generally hood-like and are, unitingthem according to the concept of the invention, provided withgutter-like eaves as the means for collecting the liquid refrigerantseparated on the baffle. According to the profiles represented, FIG. 2 ashows a hemispherical embodiment of a baffle 126 with a gutter-likeeaves 226. In FIG. 2 b, a parabolic shape baffle 226 with a gutter-likeeaves 228 is shown. In FIG. 2 c, a circular cone-like shape is providedof the baffle 326, with a gutter-like eaves 328.

While the eaves 28 et al. are shown as being in a gutter-likeconfiguration, one skilled in the art will appreciate that variousshapes for eaves could be provided without departing from the spirit ofthe present invention. A common aspect consists in that the eaves, themeans for collecting and leading off the liquid refrigerant, areprovided at the perimeter of the baffles and prevent the liquidrefrigerant on the baffle from dropping off immediately at the border ofthe baffle and being dragged as drops by the refrigerant vapor undercorrespondingly unfavorable flow conditions.

As a person skilled in the art will readily appreciate, the abovedescription is meant as an illustration of implementation of theprinciples this invention. This description is not intended to limit thescope or application of this invention in that the invention issusceptible to modification, variation and change, without departingfrom spirit of this invention, as defined in the following claims.

1. A refrigerant accumulator with a liquid separator for refrigerantcircuits comprising: a container defining a hollow interior and havingan inlet for a two-phase mixture and an outlet for refrigerant vapor; abaffle provided in an upper part of the hollow interior, the bafflehaving a collector configured to receive and direct the liquidrefrigerant into a lower region of the refrigerant accumulator.
 2. Therefrigerant accumulator of claim 1 wherein the collector is located at alower peripheral border of the baffle.
 3. The refrigerant accumulator ofclaim 1 wherein the collector is configured as an eaves gutter.
 4. Therefrigerant accumulator of claim 1 wherein the collector slopes downwardtowards a collection region.
 5. The refrigerant accumulator of claim 4further comprising an exhaust pipe for the refrigerant vapor, theexhaust pipe being supported by the container so as to be spaced apartfrom a side wall thereof.
 6. The refrigerant accumulator of claim 5wherein the collection region of the baffle is connected to the exhaustpipe.
 7. The refrigerant accumulator of claim 1 wherein the collectorslopes downward towards one side of the container.
 8. The refrigerantaccumulator of claim 1 further comprising an exhaust pipe for therefrigerant vapor, the exhaust pipe being supported by the container soas to be space apart from a side wall so as to have no direct thermalcontact therewith.
 9. The refrigerant accumulator of claim 8 wherein theexhaust pipe has a J-shape, whereby a lower opening of the exhaust pipeis provided as exhaust inlet opening arranged below the baffle.
 10. Therefrigerant accumulator of claim 9 wherein the exhaust inlet opening islocated underneath the baffle.
 11. The refrigerant accumulator of claim9 wherein the exhaust inlet opening is located within a concavity formedby the baffle.
 12. The refrigerant accumulator of claim 1 wherein thebaffle is hemi-spherical.
 13. The refrigerant accumulator of claim 1wherein the baffle is cone-shaped.
 14. The refrigerant accumulator ofclaim 1 wherein the baffle is parabolic.
 15. The refrigerant accumulatorof claim 1 wherein the container includes a cylindrical side wall.